Projection exposure apparatus using wavefront detection

Abstract

A projection exposure apparatus for imaging and printing a pattern, formed on a first object, upon a second object through a projection optical system. The projection exposure apparatus includes a storing device for storing information related to light intensity distribution on a pupil plane of the projection optical system in a reference state, and a detecting device for detecting a wavefront of the projection optical system in an arbitrary state, on the basis of the stored information.

What is claimed is:  
     
       1. A projection exposure apparatus for exposing, to a pattern, formed on a first object, a second object, through a projection optical system, said apparatus comprising: 
       storing means for storing a light intensity distribution on a pupil plane of the projection optical system in a reference state;  
       measuring means for measuring a light intensity distribution on an image plane of the projection optical system; and  
       detecting means for detecting a wavefront of the projection optical system in an arbitrary state, on the basis of the stored light intensity distribution on the pupil plane and the measured light intensity distribution on the image plane.  
     
     
       2. An apparatus according to  claim 1 , wherein said detecting means detects a wavefront aberration in the arbitrary state, in accordance with a phase restoration method. 
     
     
       3. An apparatus according to  claim 2 , wherein the stored light intensity distribution on the pupil plane is produced in accordance with the phase restoration method. 
     
     
       4. An apparatus according to  claim 3 , wherein, each time a wavefront aberration of the projection optical system is measured by said detecting means in accordance with the phase restoration method, the stored information is used as an absolute value of an amplitude distribution on the pupil plane while a measured value of a light intensity distribution on an image plane of the projection optical system in the arbitrary state is used as an absolute value of an amplitude distribution on the image plane.